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  • Author or Editor: Gregor Osterc x
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Mateja Štefančič, Franci Štampar and Gregor Osterc

The influence of two exogenously applied auxins (IAA and IBA) on the root and shoot development of leafy cuttings was analyzed at 'GiSelA 5', the dwarfing cherry rootstock. IBA (indole-3-butyric acid) hindered the callus formation in the early period of root development and it was more successful than IAA (indole-3-acetic acid) in promoting earlier root development. IBA also influenced the stronger shoot growth and the development of acrobasal type of the rooting system, and induced higher number of roots. Those parameters are very important for the quality and survival of the new plants and they are not the consequence of the higher IAA content in the rooting zones of cuttings in the first days of root development. Both auxin treatments had no effect on the final percent of the rooted cuttings neither on the survival of cuttings, but they increased the percent of rooted cuttings without callus. The root system with callus proved less qualitative, because the cuttings with such root system developed significantly less roots per rooted cutting and their shoot length was shorter than those of the cuttings without callus at both auxin treatments. Exogenously applied auxins were not crucial for root formation, however their application resulted in higher percent of more qualitative 'GiSelA 5' leafy cuttings. IBA proved as the most efficient treatment and it additionally induced earlier root formation.

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Valentina Schmitzer, Robert Veberic, Gregor Osterc and Franci Stampar

In the present study, the chemical and morphological status of eight cultivars of groundcover rose (Rosa ×hybrida) with a range of flower colors was investigated. From the methanolic extracts of rose petals collected from flowers at four developmental stages, several phenolic compounds were identified via high-performance liquid chromatography/mass spectrometry, including five anthocyanins, which are especially important for the visual attributes of rose flowers. Colorimetric parameters were also measured and correlated with total anthocyanins and cell sap pH levels. During flower development from bud to senescent stage, a significant trend was detected; lightness (L*) increased, b* decreased in all analyzed roses, and a* decreased in pink and red cultivars. Cell sap pH level increased from bud to senescent petals; fresh weight, dry weight, and water content increased to fully open stage and were then reduced in senescent petals. Total anthocyanin and quercetin content increased from bud stage to fully open flowers, and was decreased in senescent ones. However, the highest content of total phenolics was measured in buds and partially opened flowers, respectively. Three distinct groups were formed according to the content of total anthocyanins and quercetins; white cultivars were most distant from the red ones, which were similar to the pink and light red cultivars.

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Valentina Schmitzer, Robert Veberic, Gregor Osterc and Franci Stampar

The concentration of major anthocyanins, quercetins, catechin, and phenolic acids during flower development of Rosa ×hybrida L. ‘KORcrisett’ was quantified using high-performance liquid chromatography/mass spectrometry. Additionally, the changes in petal color were monitored colorimetrically at four different stages of development (bud, partially open flowers, fully open flowers, senescent flowers) and correlation was calculated between the chromaticity parameters and major/total anthocyanins. Color parameters a*, b*, and h° decreased with the progression of flower development and a*/b* ratio and lightness (L*) increased. In rose petals, a negative trend in the content of major (pelargonidin-3,5-di-O-glucoside, cyanidin-3,5-di-O-glucoside) and minor (pelargonidin-3-O-glucoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside) anthocyanins was observed during flower development. Buds contained almost threefold higher concentrations of pelargonidin-3,5-di-O-glucoside and fourfold higher concentrations of cyanidin-3,5-di-O-glucoside than senescent flowers. Buds also contained significantly more quercetins (quercetin-3-O-rutinoside, quercetin-3-O-glucoside, and quercetin-3-O-rhamnoside), catechin, and phenolic acids (gallic acid, protocatechulic acid, chlorogenic acid, caffeic acid, p-coumaric acid) than flowers of subsequent developmental stages. The most significant differences were observed in the content of gallic acid; buds contained almost sixfold higher values than senescent flowers. Correlation analysis revealed a strong correlation between chromaticity parameters a*, b*, a*/b* ratio, , L*, and major/total anthocyanins with values ranging from 0.60 to –0.84.

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Gregor Osterc, Maja Mikulic Petkovsek, Franci Stampar, Biljana Kiprovski, Blanka Ravnjak and Joze Bavcon

Common cyclamen (Cyclamen pururascens Mill.) is a very interesting species not only for various breeding programs but also as an ornamental plant. The plants possess interesting floral and foliage characteristics, nice fragrances, and a very useful flavonol profile. The last is very important from the point of view of protecting against diseases and physiological disorders. Twenty-two different genotypes originating from different regions in Slovenia were analyzed in detail, based on their floral and foliage characteristics. Anthocyanin and flavonol contents were determined using high-performance liquid chromatography (HPLC)-photodiode array-mass spectrometry (MS). Color characteristics were colorimetrically evaluated separately for petals and leaves. In terms of color measurements, significant differences among the sites of origin were shown with parameters a* and L* when petals were analyzed, and with parameter a* when leaves were analyzed. The pH of petal sap stayed within the acid range, ranging from 3.96 to 4.82. Five different anthocyanins (malvidin-3,5-diglucoside, cyanidin-3-neohesperidoside, delphinidin-3-glucoside, delphinidin-3,5-diglucoside, and delphinidine-3-rutinoside) were analyzed in flowers, and this is the first report of delphinidin metabolites naturally present in common cyclamen genotypes. In relation to plant leaves, malvidin-3,5-diglucoside, malvidin-3-rutinoside, malvidin-3-glucoside, cyanidin-3-neohesperidoside, and peonidin-3-neohesperidoside were measured. Fifteen different flavonols were determined in common cyclamen flowers and 10 different flavonols in common cyclamen leaves. Various glycosides of quercetin, myricetin, and kaempferol were analyzed, as well as isorhamnetin-3-rutinoside, laricitin-3-rutinoside, and neohesperidin. The floral and foliage characteristics of the genotypes (physical and chemical) were mainly affected by the environmental conditions of the locality of origin of the genotypes (annual disposition of temperature and precipitation, structure of the soil, etc.).